Re: [PATCH net-next 2/2] ipvs: Replace use of system_unbound_wq with system_dfl_wq

[Julian Anastasov <ja@ssi.bg>]

	Hello,

On Mon, 11 May 2026, Marco Crivellari wrote:

> This patch continues the effort to refactor workqueue APIs, which has begun
> with the changes introducing new workqueues and a new alloc_workqueue flag:
> 
>    commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
>    commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")
> 
> The point of the refactoring is to eventually alter the default behavior of
> workqueues to become unbound by default so that their workload placement is
> optimized by the scheduler.
> 
> Before that to happen, workqueue users must be converted to the better named
> new workqueues with no intended behaviour changes:
> 
>    system_wq -> system_percpu_wq
>    system_unbound_wq -> system_dfl_wq
> 
> This way the old obsolete workqueues (system_wq, system_unbound_wq) can be
> removed in the future.
> 
> Cc: Julian Anastasov <ja@ssi.bg>
> Cc: Pablo Neira Ayuso <pablo@netfilter.org>
> Cc: Florian Westphal <fw@strlen.de>
> Cc: Phil Sutter <phil@nwl.cc>
> Cc: lvs-devel@vger.kernel.org
> Cc: netfilter-devel@vger.kernel.org
> Cc: coreteam@netfilter.org
> Link: https://lore.kernel.org/all/20250221112003.1dSuoGyc@linutronix.de/
> Suggested-by: Tejun Heo <tj@kernel.org>
> Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>

	Sorry that such change was delayed but there were
many changes in IPVS for the last month. The last that may
delay this patch is:

v3 of "ipvs: avoid possible loop in ip_vs_dst_event on resizing"
https://lore.kernel.org/lvs-devel/20260510104605.24218-1-ja@ssi.bg/T/#u

	May be we have to wait this change to reach net and
net-next. Also, we can reconsider which queue to use, these works
resize hash tables and call synchronize_rcu(), should we switch to
system_dfl_long_wq if such job is considered "long" ?

> ---
>  net/netfilter/ipvs/ip_vs_conn.c |  4 ++--
>  net/netfilter/ipvs/ip_vs_ctl.c  | 10 +++++-----
>  2 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
> index 9ea6b4fa78bf..2625c0379556 100644
> --- a/net/netfilter/ipvs/ip_vs_conn.c
> +++ b/net/netfilter/ipvs/ip_vs_conn.c
> @@ -285,7 +285,7 @@ static inline int ip_vs_conn_hash(struct ip_vs_conn *cp)
>  	/* Schedule resizing if load increases */
>  	if (atomic_read(&ipvs->conn_count) > t->u_thresh &&
>  	    !test_and_set_bit(IP_VS_WORK_CONN_RESIZE, &ipvs->work_flags))
> -		mod_delayed_work(system_unbound_wq, &ipvs->conn_resize_work, 0);
> +		mod_delayed_work(system_dfl_wq, &ipvs->conn_resize_work, 0);
>  
>  	return ret;
>  }
> @@ -916,7 +916,7 @@ static void conn_resize_work_handler(struct work_struct *work)
>  
>  out:
>  	/* Monitor if we need to shrink table */
> -	queue_delayed_work(system_unbound_wq, &ipvs->conn_resize_work,
> +	queue_delayed_work(system_dfl_wq, &ipvs->conn_resize_work,
>  			   more_work ? 1 : 2 * HZ);
>  }
>  
> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> index c7c7f6a7a9f6..f8fe1c8981d8 100644
> --- a/net/netfilter/ipvs/ip_vs_ctl.c
> +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> @@ -800,7 +800,7 @@ static void svc_resize_work_handler(struct work_struct *work)
>  	if (!READ_ONCE(ipvs->enable) || !more_work ||
>  	    test_bit(IP_VS_WORK_SVC_NORESIZE, &ipvs->work_flags))
>  		return;
> -	queue_delayed_work(system_unbound_wq, &ipvs->svc_resize_work, 1);
> +	queue_delayed_work(system_dfl_wq, &ipvs->svc_resize_work, 1);
>  }
>  
>  static inline void
> @@ -1833,7 +1833,7 @@ ip_vs_add_service(struct netns_ipvs *ipvs, struct ip_vs_service_user_kern *u,
>  	/* Schedule resize work */
>  	if (t && ip_vs_get_num_services(ipvs) > t->u_thresh &&
>  	    !test_and_set_bit(IP_VS_WORK_SVC_RESIZE, &ipvs->work_flags))
> -		queue_delayed_work(system_unbound_wq, &ipvs->svc_resize_work,
> +		queue_delayed_work(system_dfl_wq, &ipvs->svc_resize_work,
>  				   1);
>  
>  	*svc_p = svc;
> @@ -2078,7 +2078,7 @@ static int ip_vs_del_service(struct ip_vs_service *svc)
>  	} else if (ns <= t->l_thresh &&
>  		   !test_and_set_bit(IP_VS_WORK_SVC_RESIZE,
>  				     &ipvs->work_flags)) {
> -		queue_delayed_work(system_unbound_wq, &ipvs->svc_resize_work,
> +		queue_delayed_work(system_dfl_wq, &ipvs->svc_resize_work,
>  				   1);
>  	}
>  	return 0;
> @@ -2511,7 +2511,7 @@ static int ipvs_proc_conn_lfactor(const struct ctl_table *table, int write,
>  		} else {
>  			WRITE_ONCE(*valp, val);
>  			if (rcu_access_pointer(ipvs->conn_tab))
> -				mod_delayed_work(system_unbound_wq,
> +				mod_delayed_work(system_dfl_wq,
>  						 &ipvs->conn_resize_work, 0);
>  		}
>  	}
> @@ -2543,7 +2543,7 @@ static int ipvs_proc_svc_lfactor(const struct ctl_table *table, int write,
>  			    READ_ONCE(ipvs->enable) &&
>  			    !test_bit(IP_VS_WORK_SVC_NORESIZE,
>  				      &ipvs->work_flags))
> -				mod_delayed_work(system_unbound_wq,
> +				mod_delayed_work(system_dfl_wq,
>  						 &ipvs->svc_resize_work, 0);
>  			mutex_unlock(&ipvs->service_mutex);
>  		}
> -- 
> 2.54.0

Regards

--
Julian Anastasov <ja@ssi.bg>